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Dealing with slurry – is there a breakthrough on the horizon?

Dealing with the huge amounts of by-products from livestock farming does not come cheap.

Maintaining all the infrastructure involved in storing and processing slurry and silage liquor requires significant investment and a new slurry store for a 100 or more milking cows can cost tens of thousands of pounds.

The economic struggles of farmers, particularly dairy, have been widely publicised and farms with insecure futures just cannot justify significant expenditure.

The average price of milk in most of the UK has fallen by at least 14 per cent over the past five years and many farmers have no alternative but to sell milk at a loss.

It is a sad fact that some farmers are being paid 10p a litre less than it costs them to produce it and, ironically, fresh milk is still all too often cheaper than bottled water.

Since the year 2000, the number of dairy farmers in England and Wales has fallen from more than 25,000 to 9,383 and last year another one in ten dairy farmers quit.

Around 60 years ago, when milk production was expanding, economical cow kennels were being introduced, followed soon after by large cubicle sheds with automated scrapping systems or slatted floors. These methods did away with demands for huge quantities of bedding straw in yarded housing systems.

That was when the problems of dealing with watery farm slurry began and the urgent need to prevent run-off into nearby streams compounded, in recent times, by the legislative demands of cross compliance.

Afonydd Cymru, a body which represents six river trusts in Wales, said farmers faced with the choice between a new slurry store or a £10,000 pollution fine would opt for the latter.

Comments made by inspectors in Wales echo the view that fines can be seen as part of running costs.

"Where we have ongoing non-compliance, and penalties imposed are seen as a running cost, the traditional enforcement solutions have to be challenged," one inspector wrote.

Pollution from farms has and still is being urgently addressed, according to experts and campaign groups.

"Poor regulation and enforcement by government is allowing this to happen."

National Resources Wales has spoken out against pollution from farms and has written to the Welsh Government about the problem.

In a statement the Environment Agency reported: “Agriculture uses 70 per cent of the land and farmers have a major impact on the environment. Most farmers act responsibly and we work with the industry to respond to incidents, tackle the root causes of pollution and promote good practice.

“But where farmers are responsible for serious pollution incidents, we will not hesitate to take enforcement action, including prosecution. Agriculture is the single biggest source of serious pollution incidents and all farmers have a duty to prevent it.”

The only way a farmer can dispose of the farm effluent, swollen by heavy rainfalls, is to spread it on grassland intended for conservation or on tillage areas – but this cannot be done if the land is already saturated or if the ground is frozen, due to problems of run-off.

Could there yet be light at the end of the tunnel?

Addressing the North Pembrokeshire Grassland Society, John Owen, farm manager of the Coleg Sir Gâr’s Gelli Aur campus, revealed details of an innovative project underway to address the agricultural industry's impact on the environment by developing an effective dewatering and purification system to manage slurry.

The project, now at an advanced stage of development at the College farm, has received funding through the Welsh Government’s Rural Communities Development Programme 2014-2020, which is funded by the European Agricultural Fund for rural Development and the Welsh Government.

The project, being spearheaded by a Swansea based company specialising in electrochemical-based water treatments, will apply innovative and proven concept technology to reduce air and water pollution to reduce the overall volume of slurry by up to 80 per cent.

A de-watering and purification system is used to filter slurry, transforming the water to a suitable quality for recycling or discharging to a clean watercourse.

The system will also utilise nutrients from the slurry to produce good quality fertiliser.

John Owen said: “With the intensification of the dairy industry, slurry management is becoming an increasing issue for farmers and the environment. We aim to reduce significantly the risk of air and water pollution at the same time as maximising the recycling nutrient value. This development process will considerably reduce storage of slurry on farms as well as handling costs.

“Efficiently extracting nutrients from manures could save part of the cost of commercial fertilisers and reduce serious environmental impact. However, poor manure management can cause pollutants, including nutrients, to enter the water cycle through run-off or drainage.”

The project also aims to design, develop and validate an economically viable system that will be made available commercially and used on farms.

Natural Resources Wales (NRW) states that the number of pollution incidents caused by dairy and beef farms across Wales has fluctuated between 85 and 120 for each of the last six years.

Wet winters and a significant downturn in the dairy market have added to the pressure on the environment and farmers; reducing their capacity to invest in slurry and silage store management and over 60 per cent of the incidents involving pollution during the last three years took place within the milk field of Carmarthenshire and Pembrokeshire.

Under the threat of coming within a nitrate vulnerable zone, farmers and researchers have long struggled to find a lasting solution by developing a workable, cost-effective form of separating the solids from the liquids.

Weeping walls, screening, screw presses and lagoons have all been extensively tried but, in most cases have been found to be painfully slow and dauntingly ineffective.

Well tried methods have seen slurry being smeared over a mesh screen, the more liquid fraction passes through the screen and the solid components are directed out of the separator where they can then be stored separately.

With a screw press separator, slurry is squeezed by a large screw-shaped plunger, the liquid portion is extracted and the solids are directed into a separate, solid manure store. By removing the solid portion a 15-20 per cent reduction in slurry volume is expected.

When considering which system is most suitable, annual service, maintenance and running costs should be considered.

There is a limited amount of nutrient partitioning. There will be more available nitrogen and potash (as they are water soluble) in the liquid fraction and more organic (slow release) nitrogen and phosphate in the solid component. The liquid portion is a lower dry matter than raw slurry and so it leaves less contamination in the sward when it is applied to land.

John Owen explained that the technique, now being perfected, takes advantage of the fact that manure, like almost everything else in biology, is made up mostly of water. Extracting that water can reduce the sheer volume enormously, making it easier to store and discard.

What’s more, this method frees up some of the most useful agricultural substances in the manure and, with the full treatment regime, water extracted from the manure can be fed back to livestock as clean drinking water.

That could have a profound impact on the profitability of most farmed foods. It could also do a lot for air quality, which is damaged by release of ammonia and other molecules from these billions of gallons of manure.

This is the sort of basic breakthrough that could have major impacts, particularly over high rainfall areas of west Wales and, it is anticipated, the proof of the pudding will be available for farmers to see and evaluate later this summer.

Ipsoregulated

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